Learning about Control of Optimization -- for dummies please

[Roland Smith]

On Wed, Aug 05, 2009 at 10:54:07AM +0100, David Southwell wrote:
> I have found http://docs.freebsd.org/info/gcc/gcc.info.Optimize_Options.html.
> 
> I am about to build a new kernel am starting to dig a bit deeper into things I 
> have, until now, taken for granted.
> 
> The above link is very informative in technical terms about how to control 
> optimization but I find it difficult to interpret the info in a way that tells 
> me what might work best on my own system (Intel quad Core) with 8G of ram.

The build system takes care of that, once you have set the correct
CPUTYPE in /etc/make.conf. For a quad-core, set CPUTYPE=nocona. See
make.conf(5), /usr/src/share/mk/bsd.cpu.mk and
/usr/src/sys/conf/kern.pre.mk.

Additionally, compiler settings for building the kernel can be set with
COPTFLAGS in /etc/make.conf. Using anything other than -O or -O2 is
not guaranteed to work. If you don't know what you are doing, do not use
COPTFLAGS and stick with the defaults that the build system generates. 

Roland
-- 
R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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